Transmission for use in motor vehicle

ABSTRACT

A transmission for use in a motor vehicle having a torque converter; an auxiliary speed change-gear assembly coaxial with the torque converter; an intermediate shaft extending through the auxiliary speed change-gear assembly; a countershaft extending in parallel to the intermediate shaft of the auxiliary speed change-gear assembly; and a final reduction-gear assembly for transmitting a driving force from the countershaft to wheel axles. The auxiliary speed change-gear assembly provides a plurality of forward speed range drives including overdrive and reverse drive and has an output driving gear. A driven gear is mounted on the countershaft and meshes with the driving gear. The transmission has at least one thrust bearing mounted on the intermediate shaft of the auxiliary speed change-gear assembly for rotatably supporting the driving gear and a member threadably engaged into one end of an auxiliary speed change-gear assembly casing for asserting a predetermined force on the bearing supporting the driving gear. Preferably, the at least one bearing comprises a first pair of counterbalancing thrust bearings mounted on the intermediate shaft rotatably supporting the driving gear. A second pair of thrust bearings are provided for receiving thrust-reacting forces from the first pair of bearings. The force-exerting member is preferably threadably engaged into the one end of the auxiliary speed change-gear assembly casing remote from the torque converter, exerts a predetermined force on one bearing of the second pair, and is accessible from outside the casing.

BACKGROUND OF THE INVENTION

This invention generally relates to a transmission for use in a motorvehicle, and more particularly to a transmission having automatic speedchange-gear and final reduction-gear assemblies for use in a motorvehicle with an engine mounted transversely therein.

With a view to affording a motor vehicle increased space while providingfuel efficiency and meeting air pollution and noise abatement standards,motor vehicles with front engine, front-wheel drive systems have becomerecognized as providing numerous advantages. Such advantages includecompactness in size, reduction in noise, reduction in the weight of themotor vehicle, and reduction in fuel consumption.

If an automatic speed change-gear assembly for providing four forwardspeed drives and a reverse drive is incorporated in a transmission for afront-wheel driving system in a motor vehicle with a laterally mountedengine, the overall length of the transmission increases. Because ofthis, the transmission may interfere with the suspension system of themotor vehicle. This problem is most serious in motor vehicles commonlyreferred to as compact cars.

The difficulties encountered in providing a satisfactory transmission ofthis type in a compact car are even more compounded when it is desiredto provide an overdrive speed range.

SUMMARY OF THE INVENTION

Accordingly, it is a primary object of this invention to provide atransmission for use in a motor vehicle having at least an automaticspeed change-gear assembly for providing four forward speed drives and areverse drive which minimizes the length of the transmission andprovides freedom from interference with the vehicular suspension system.

It is another object of the invention to provide a transmission systemfor use in a motor vehicle having an automatic speed change-gearassembly for providing a plurality of forward speed drives, includingoverdrive, and a reverse drive which minimizes the length of thetransmission and results in freedom from interference with the vehicularsuspension system.

A still further object of this invention is to provide a transmissionsystem which is compact in size, ensures improved fitting of thecomponents of the transmission under various thrust and torque loads,and minimizes manufacturing costs.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by practice of the invention. The objectsand advantages of the invention may be realized and attained by means ofthe instrumentalities and combinations particularly pointed out in theappended claims.

To achieve the foregoing objects and in accordance with the purpose ofthe invention, as embodied and broadly described herein, thetransmission of this invention for use in a motor vehicle comprises atorque converter, an auxiliary speed change-gear assembly coaxial withthe torque converter and having an output means with a driving gear anda plurality of forward speed range drives including overdrive, and areverse drive, for transmitting a driving force from the torqueconverter to the output means, an intermediate shaft extending throughthe auxiliary speed change-gear assembly, a driven gear mounted on thecountershaft and meshing with the driving gear, a final reduction-gearassembly for transmitting a driving force from the countershaft to thewheel axles of the motor vehicle, at least one thrust bearing mounted onthe intermediate shaft of the auxiliary speed change-gear assembly androtatably supporting the driving gear, and, means for exerting apredetermined force on the at least one thrust bearing.

As here embodied, means for exerting a predetermined force is a memberthreadably engaged into one end of an auxiliary speed change-gearassembly casing.

Preferably, the at least one bearing comprises a first pair ofcounterbalancing thrust bearings mounted on the intermediate shaft androtatably supporting the first gear and a second pair of thrust bearingsfor receiving thrust-reacting forces from the first pair of bearings.

It is also preferred that each bearing of the second bearing pair havean outer race fixed to a stationary portion of the auxiliary speedchange-gear assembly and an inner race mounted on the intermediate shaftand adapted to receive the thrust-reacting forces from the correspondingbearing of the first pair.

As is preferred, one bearing of the second bearing pair is mounted onthe intermediate shaft at the end of the auxiliary speed change-gearassembly casing remote from the torque converter and the member isthreadably engaged at that remote end to exert a predetermined force onthat one bearing.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate an embodiment of the inventionand, together with the description, serve to explain the principles ofthe invention.

FIG. 1 is a schematic view of one embodiment of a transmission inaccordance with the present invention for use in a motor vehicle;

FIGS. 2a and 2b are cross-sectional views showing a detailed arrangementof the transmission of FIG. 1;

FIG. 3 is a fragmented side view of the casing for the auxiliary speedchange-gear assembly of the transmission of FIGS. 1 and 2a and 2b; and,

FIG. 4 is a schematic and perspective view of the transmission of FIGS.1 and 2a and 2b in relationship to the wheel axles and suspension systemof a motor vehicle.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Reference will now be made in detail to the present preferred embodimentof the invention, an example of which is illustrated in the accompanyingdrawings.

Referring now to FIGS. 1 and 2a and 2b, it may be seen that thetransmission according to this invention comprises an automatic speedchange-gear assembly 70 having a torque converter 3, preferably of afluid-type, an auxiliary speed change-gear assembly 11, a transmissiongear assembly 71 and a final reduction-gear assembly 60.

As here embodied, the automatic speed change-gear assembly 70 ispositioned laterally to an engine 1 for the motor vehicle, with engine 1being positioned transversely with respect to the axles of the vehicularwheels. The torque converter 3 is positioned laterally adjacent engine 1and includes a pump impeller 4, a stator 7, and a turbine runner 8. Anoutput shaft 2 of engine 1 is coupled to the pump impeller 4 while thestator 7 is connected, such as by a one-way clutch 5, to a stationaryportion 6 of the torque converter 3.

As here embodied, the auxiliary speed change-gear assembly 11 forproviding the desired drive speed ranges includes an underdrive gearunit 12 and an overdrive gear unit 13, both of which are mountedcoaxially with the output shaft 2 of engine 1. An intermediate shaft 40extends through the center of auxiliary speed change-gear assembly 11and is used to transmit power from the underdrive gear unit 12 to theoverdrive gear unit 13.

The underdrive gear unit 12 is positioned laterally adjacent the torqueconverter 3 and has an input shaft 14 coaxial to intermediate shaft 40and coupled to turbine runner 8 of the torque converter. Preferably, theunderdrive gear unit 12 comprises first and second planetary gearmechanisms 15 and 16, respectively. The first planetary gear mechanism15 has a sun gear 17, planetary pinions 18 meshing with the sun gear 17,a ring gear 19 meshing with pinions 18, and a carrier 20 rotatablysupporting ring gear 19 and planetary pinions 18. Preferably, carrier 20is connected to intermediate shaft 40 by being spline-fitted thereon.

The second planetary gear 16 has a sun gear 30, planetary pinions 31, aring gear 32 meshing with pinions 31, and a carrier 33 rotatablysupporting planetary pinions 31. Sun gear 30 is integrally connected tosun gear 17 by a sun gear shaft 27. Preferably, the sun gear shaft 27 isa hollow shaft surrounding intermediate shaft 40 and is coaxial with theinput shaft 14. The sun gears 17 and 30 are integrally formed on thissun gear shaft 27, by forming teeth at opposite ends thereof. Ring gear32 is preferably connected to intermediate shaft 40 by beingspline-fitted thereon through hub 89.

The overdrive gear unit 13 of auxiliary speed change-gear assembly 11 iscoaxially positioned on the side of the underdrive gear unit 12 oppositefrom the torque converter 3. The overdrive gear unit 13 includes atleast a planetary gear mechanism 41, which in turn has a sun gear 42,planetary pinions 43, a ring gear 44, and a carrier 45 rotatablysupporting planetary pinions 43 and coupled to intermediate shaft 40.Preferably, carrier 45 is formed integrally with shaft 40. As hereinembodied, the input element for the overdrive gear unit 13 comprisescarrier 45 while the output element of the overdrive gear unit 13comprises ring gear 44.

To transmit power from the auxiliary speed change-gear assembly 11 tothe transmission gear unit 71, assembly 11 has output means comprising adriving gear 53. As herein embodied, output gear 53 is spline-fitted ona member provided between planetary gear unit 41 and cylindrical casing76 as well as being integrally connected to the ring gear 44.

A fixed casing 73 houses the fluid-type torque converter 3, theunderdrive gear unit 12, transmission gear unit 71. Final reduction gearunit 60 is located under transmission gear unit 71. Auxiliary casing 74substantially houses overdrive unit 13 coaxially with underdrive unit12. As best seen in FIG. 2a, the underdrive unit 12 is positioned incasing 73 on the engine side thereof, while overdrive gear unit 13 isdisposed in a space defined by auxiliary casing 74 with the cylindricalcasing 76. The planetary gear unit 41 for overdrive unit 13 ispositioned substantially in the central portion of this space. Casing 73is bolted at one end to the right side surface of the engine at severalpoints and bolted at the other end to auxiliary casing 74 at severalpoints such as at 77 to enclose the cylindrical casing 76.

As here embodied, the cylindrical casing 76 is an inverted U-shapedconfiguration fitted in the diametrically equal inner cylindricalportions defined by inner walls 98a and 99b of auxiliary casing 74 andcasing 73 in the joint portion therebetween. Preferably, cylindricalcasing 76 is bolted to auxiliary casing 74, such as at two or morepoints 99. During assembly, the overdrive gear unit 13 and intermediateshaft 40 are placed first in auxiliary casing 74, then cylindricalcasing 76 is fitted into auxiliary casing 74, which is in turn fittedinto cylindrical portion 98b of casing 73, and bolted thereto such as at77 shown in FIG. 2a.

To accomplish the speed-change actions of the auxiliary speedchange-gear assembly 11, there are provided friction-engaging meanswhich interact with the different members of the underdrive gear unit 12and overdrive gear unit 13. An oil pump 78 is fixed to casing 73, asbolted at 75, and serves as an oil pressure and a working oil, such asby an oil pressure control unit (not shown) to respectivefriction-engaging means and the fluid torque converter. Thefriction-engaging means include clutches 23, 24 and 48, one-way clutches34, 36 and 54, and brake units 25, 35, 37, and 49. A detaileddescription of the friction-engaging elements for operation of theauxiliary speed change-gear assembly 11 will now be made with referenceto FIGS. 1 and 2a and 2b and to the following table:

                  TABLE                                                           ______________________________________                                               Clutch and Brake Units                                                 Speed Range                                                                            23     24    25  35   37  34  36   48  49  54                        ______________________________________                                        First Speed                                                                            0                     0       Δ                                                                            0       Δ                   Second Speed                                                                           0            0   0        Δ  0       Δ                   Third Speed                                                                            0      0                           0       Δ                   Overdrive                                                                              0      0                           0                                 Reverse         0              0            0       Δ                   ______________________________________                                    

The above table shows the operation at the respective transmissionstages of these friction-engaging means, in which the designation "0"represents the engagement of the respective clutch and brake units,while the designation "Δ" represents the engagement of the respectiveone-way clutch units. As is conventional, the engagement anddisengagement of each clutch and brake unit is governed by supply of oilpressure from an oil pressure supply unit to an oil pressureservomechanism and discharge of such oil pressure from thatservomechanism. The extreme left column identifies the various speedranges associated with the transmission system, that is first, second,third, overdrive and reverse, and the top column identifies theparticular transmission element. It is thus seen, for example, that infirst speed range, transmission elements 23, 37, 36, 48 and 54 areengaged, and transmission elements 24, 25, 35, 34 and 49 are not engaged(released).

As schematically shown in FIG. 1, and more particularly depicted in FIG.2a, clutch unit 23 for use in all direct drives controls the connectionbetween the input shaft 14 and ring gear 19, and clutch unit 24 for usein third speed, overdrive, and reverse, controls the connection of inputshaft 14 with sun gear shaft 27 through the sun gear 17. Brake unit 25for use in second speed controls the connection of the sun gear 17 withfixed casing 73.

As herein embodied, clutches 23 and 24 are positioned on the engine sideof the underdrive gear unit 12. The clutch units 23 and 24 are connectedto each other through a drum 79 and a hub 80 which are fixedly attachedto input shaft 14, as by welding, with the clutch unit 24 being housedin drum or cylinder 81. Cylinder 81 in turn is rigidly secured to casing73. A brake band 82 of brake unit 25 is wound to the outer periphery ofcylinder 81 of clutch unit 24 in order to arrest sun gear shaft 27 to alocked position during the second speed drive. Because brake band 82 forbrake unit 25 is operable only for applying a braking action to theengine, i.e., by operation of one-way clutch 34 during the running ofthe vehicle, the capacity and width of brake band 82 can be reduced aswell as the servopiston for the brake unit. A reduced brake band affordsan effective use of the space radially outward of drum 81. For example,the bolt 75 for oil pump 78 can be positioned radially inwardly of thedrive casing 73, with a reduction in the outer diameter for the drivecasing 73.

Sun gear shaft 27 is spline-fitted on the outer periphery of drum 81 ofclutch unit 24, such as through a drive member 83. Sun gear 17 is alsopreferably spline-fitted to drive member 83. Ring gear 19 is connectedto clutch unit 23. Preferably, ring gear 19 has an outer peripheralsurface spline-fitted to clutch unit 23 and an inner peripheral surfacespline-fitted to a disc 88 disposed between carrier 20 and the end ofinput shaft 14. Disc 88 is spline-fitted onto intermediate shaft 40 sothat it may receive thrust loads.

One-way clutch 34 for use in second speed and brake unit 35 for use insecond speed are provided in series relationship to each other betweenthe sun gear shaft 27 and casing 73. One-way clutch 36 for use in firstspeed and brake unit 37 for use in first speed and reverse are providedin parallel to each other between the carrier 33 and casing 76. One-wayclutches 34 and 36 are coaxial with each other as viewed in the radialdirection and placed one upon another as viewed in the axial direction.More specifically, one-way clutch 36 is provided between the planetarygear units 15 and 16 as viewed in the axial direction while the brakeunit 37 is positioned above the outer periphery of the planetary gearunit 16.

Because the one-way clutches 34 and 36 are positioned between planetarygear units 15 and 16, as viewed in the axial direction of thetransmission, and because one-way clutch 36 is positioned outwardly ofone-way clutch 34, as viewed in the radial direction of thetransmission, the length of the transmission is reduced and effectiveuse of the space radially outwardly of the one-way clutch 34 isachieved. Additionally, this arrangement allows a lubricating oil forone-way clutch 34 to also be used for one-way clutch 36. Such placementthus results in the overall compactness in size of the transmission ofthis invention, particularly reduction in the length of the auxiliaryspeed change-gear assembly 11.

Carrier 33 of planetary gear unit 16 is connected to brake unit 37 byhub 91 which is formed integrally with an inner race 90 of one-wayclutch 36 for locking during the first speed drive range when one-wayclutch 36 is brought into engagement. One-way clutch 34, which isbrought into engagement with sun gear shaft 27 during the second speeddrive range, is disposed between the radially inner surface of innerrace 90 of one-way clutch 36 and sun gear shaft 27. An outer race 92 ofone-way clutch 36 is spline-fitted to casing 73 on the right side ofbrake unit 37, as shown in FIG. 2a. This outer race 92 is provided witha servomechanism 95 for brake unit 35 which governs the connection ofthe outer race 93 of one-way clutch unit 34 to casing 73 through hub 94during second speed drive range.

As herein embodied, the servomechanism 95 for brake unit 35 includes acylinder 121, a piston 96 housed in cylinder 121, and an oil conduit 97through which oil pressure is introduced into the chamber of theservomechanism. Brake cylinder 121 is formed integrally with the outerrace 92 of one-way clutch 36 and is retained in place by spline-fittingits outer peripheral surface in an inner peripheral surface 122 of drivecasing 73. This produces many advantages in minimizing components aswell as effectively using space.

For a duration during which the brake unit 35 is maintained in theengagement position during second speed drive, one-way clutch 36, foruse in the first speed drive range, is maintained in disengagedposition. For a duration in which one-way clutch 36 is maintained inengagement during the first speed drive range, brake unit 35 for thesecond speed drive range is maintained in disengaging position.Eccentricity of one clutch accruing from the engagement thereof may bethus relieved by the spline of the other clutch maintained indisengagement.

The brake unit 37 has a servomechanism 103 disposed in cylindricalcasing 76 which has oil passages 105 for supplying oil pressure to thatservomechanism. Cylindrical casing 76 has a recess which defines acylinder 124. Cylinder 124 accommodates a piston 125 for constituting aservomechanism of the brake unit 37. Cylinder 124 is provided radiallyoutwardly of planetary gear unit 16 substantially in superimposedrelation thereto in the axial direction as shown in FIG. 2a. Because thecylinder 124 is formed in cylindrical casing 76 and positioned radiallyoutwardly of planetary gear unit 16, this arrangement facilitatesplacement of oil pressure supply circuit 105 and contributes toreduction in the size of the transmission in the axial direction.

In accordance with the invention, brake unit 37 for use in first speedand reverse, and brake unit 35 for use in second speed, mutually use theinner peripheral surface 122 of casing 73 provided with splined grooves.Consequently use of a friction member common to both brake units 37 and35 is thus permitted allowing for a less costly device and improvedfitting. Additionally, this arrangement allows the outer periphery ofthe brake cylinder 121 to be retained in position by spline fitting itsouter peripheral surface in the inner peripheral surface 122 of thecasing 73 using the common spline grooves.

For the overdrive gear unit 13, clutch unit 48 used during first,second, third and reverse speeds governs the connection of carrier 45with sun gear 42, while brake unit 49 used during overdrive governs theconnection of sun gear 42 with auxiliary casing 74. One-way clutch 54used during first, second, third and reverse speeds governs theconnection of carrier 45 and ring gear 44 with the output gear 53. Theclutch unit 48 is provided at the portion of the auxiliary casing 74remote from the torque converter 3. A cylindrical hub 101 is secured toclutch unit 48 and spline-fitted to the brake unit 49. Brake unit 49 islocated between the inner peripheral wall of auxiliary casing 74 and theplanetary gear unit 41 and is used to secure sun gear 42 to auxiliarycasing 74. Gear 42 is in mesh with pinions 43, supported through bushing100 by intermediate shaft 40, and connected by cylindrical hub 101 tobrake unit 49.

As herein embodied, the brake unit 49 has a servomechanism 102 disposedwithin cylindrical casing 76, which in turn has oil passages 104 forsupplying oil pressure to the servomechanism 102. Servomechanism 102includes a piston 135 and return springs 136 for piston 135. The returnsprings are retained in holes 137 provided in the auxiliary casing 74,as shown in FIG. 3, and positioned radially outwardly of a frictionmember in brake unit 49. This arrangement dispenses with the return seatand a snap ring which are normally needed, such as in brake unit 37. Theholes 137 for retaining return springs 136 utilize a spacing betweenbolt holes 138, as shown in FIG. 3, provided in the peripheral portionof auxiliary casing 74. Accordingly, best use is made of the space inthe circumferential direction of auxiliary casing 74.

The one-way clutch 54 is brought into engagement during direct drive andgoverns the connection of carrier 45 and ring gear 44 with output gear53. This clutch is disposed between the carrier 45 and output gear 53 asviewed in the axial direction. As viewed radially, one-way clutch 54 isdisposed between the output gear 53 and the intermediate shaft 40.One-way clutch 54 allows the relative rotation of the overdrive unitduring overdrive while transmitting force directly from the intermediateshaft 40 to the output gear 53 at the time of direct underdrive, i.e.,the first to third speed drive ranges. By such an arrangement theservice life of planetary gear unit 41 can be extended.

In order to provide the above configuration, the transmission of thisinvention further comprises bearings for rotatably supporting the outputgear 53. As here embodied, thrust bearings 108 and 109 are placedbetween intermediate shaft 40 and output gear 53. Bearing 109 adjoinsthe thrust bearing 108 and contacts carrier 45. The bearings 108 and 109are arranged so as to receive a thrust acting on the intermediate shaft40 in the opposite directions when a vehicle is run forward or backward.The one-way clutch 54 is positioned radially between intermediate shaft40 and output gear 53 through bearings 108 and 109. Accordingly theinner and outer races of this one-way clutch 54 are positively supportedby the bearings with assurance of a reliable centering. Furthermore,lubricating oil fed to the bearings located radially inwardly of outputgear 53 can be introduced via the wall surface between the output gear53 and carrier 45 to one-way clutch 54, by virtue of a large centrifugaloil pressure, whereas a usage rate of the lubricating oil is greatlyincreased. Since the one-way clutch 54 may be placed in this arrangementwithin the driving gear 53 which serves as the output of the auxiliaryspeed change-gear assembly 11, a more compact overdrive unit 13 can beachieved, including reduction in the length of the transmission.

In accordance with the invention, the transmission further comprisesbearings for receiving the thrust-reacting forces from the bearingsrotatably supporting the output gear. As here embodied, these bearingscomprise thrust bearings 106 and 107 positioned on opposite sides of thebearings 108 and 109. Each bearing 106 and 107 has an outer race fixedto a stationary portion of the auxiliary speed change-gear assembly andan inner race mounted on the intermediate shaft 40 and adapted toreceive the thrust-reacting forces from the corresponding bearings 109and 108. Preferably, all of the thrust bearings 106 through 109 areroller bearings.

To the effect that the intermediate shaft 40 is rotatably supported atone end of the overdrive gear mechanism remote from the underdrive gearmechanism by casing 73 and auxiliary casing 74, the thrust bearing 106is placed between that end of intermediate shaft 40 and auxiliary casing74. The bearing 107 is placed between the intermediate shaft 40 andcylindrical casing 76 for supporting shaft 40 toward its other end.Consequently, these thrust bearings 106 and 107 are so arranged toreceive a thrust acting on the intermediate shaft 40 in the oppositedirections when a vehicle is run forward or backward.

Owing to the axially longer length of bearings 108 and 109, anymomentary load due to thrust occurring in the output gear 53 is receivedby those bearings 108 and 109. The reacting force of bearings 108 and109 is received by casings 76 and 74 through bearings 107 and 106.

Furthermore, as here embodied, an annular hole 139 is provided withincylindrical casing 76 in the central portion of the axially inner endsurface thereof, so that any leftward thrust, as viewed in FIG. 2a, ofthe planetary gear units 15 and 16 is transmitted via the ring gear 32of planetary gear unit 16 to inner race 140 of thrust bearing 107. Sincering gear 32 is spline-fitted on intermediate shaft 40, a relativerotational difference between ring gear 32 and inner race 140 of bearing107 does not occur. As may be seen, planetary gear units 15 and 16require neither thrust bearings nor thrust races, resulting in a lesscostly device as well as reduction in the length of the device. Althoughthe inner race of bearing 108 positioned between output gear 53 andintermediate shaft 40 is in engagement with inner race 140 of bearing107, the thrust arising in bearing 108 is offset by the thrust from ringgear 32. An excess of the thrust generated by output gear 53 is receivedby cylindrical case 76, without a risk of its being exerted on ring gear32.

A difference in rotation between the output gear 53 and intermediateshaft 40 arises only in the overdrive speed range. If i represents theoverdrive gear ratio and n is the r.p.m. of the intermediate shaft, thena difference in rotation therebetween is (1-i)N and of a small value. Atorque transmitted from the output gear 53 at the time is iT, with aninput torque from intermediate shaft 40 being T. Since this value isnormally small, the bearings 108 and 109 can comprise bearings of smallcapacity and yet achieve their necessary function. In addition, byvirtue of this invention, the bearings 108 and 109 are mounted radiallyinwardly of the output gear 53 for the most effective use of that innerspace. The intermediate shaft 40, furthermore, is positively supportedby the bearings 106 through 109 with a reliable centering of thecomponents of the auxiliary speed-change gear assembly 11.

In accordance with the invention, the transmission further comprisesmeans for exerting a predetermined force on the bearing rotatablysupporting the output gear. As herein embodied, the means for exerting apredetermined force comprises a member threadably engaged into astationary end of the auxiliary speed change-gear assembly 11.Preferably, a threaded hole 128 is provided in auxiliary case 74 in thecentral portion of the axially outer end surface thereof and a nut 129is threaded into hole 128. The rightward force, as seen in FIG. 2a,exerted by nut 129 acts on the intermediate shaft 40 by way of thrustbearing 106. Preload force is thus exerted on all of the thrust bearings106 through 109. As can be seen from FIG. 2a, exerting a predeterminedforce on the bearings 106 through 109 by means of a nut 129 which isaccessible from outside the transmission housing allows for an improvedand easier fitting of the overdrive gear unit to the auxiliary speedchange-gear assembly.

In the described embodiment for providing a predetermined force on thethrust bearings 106 through 109 by means of nut 129, a radial hole 130for a lubrication circuit is provided in the nut 129 so that alubricating oil can be supplied through hole 130 to the inner peripheralsurface 131 of nut 129. This inner peripheral surface 131 acts as asliding surface relative to a seal ring 132 for intermediate shaft 40. Aseal member, such as O-ring 141, is provided in the threaded hole 128for ensuring proper sealing between the auxiliary casing 74 and the nut129. By doing so, the need to provide such a sealing member for thelubrication circuit is eliminated. Because of the preload acting on thethrust bearings 106 through 109, the centering between the intermediateshaft 40 and the casings 73 and 74 is properly accomplished, thusproviding an even more improved sealing between the nut 129 and theintermediate shaft 40. Furthermore, because of the hole 130, thelubrication of the intermediate shaft starts from the end portionthereof to which no drive force is transmitted, thus eliminating a needto provide a lubrication hole midway in the intermediate shaft to whicha drive force is transmitted. Increased strength to the intermediateshaft 40 is, therefore, achieved.

Intermediate shaft 40, as herein embodied, has an axial hole 147 runningthrough the center thereof, and radial holes 148 and 149 running fromthe axial hole to the outer peripheral surface of the shaft at a spacingin the axial direction from each other. A lubricating oil is introducedthrough axial hole 147 and radial hole 148 into the bearings 108 and 109for lubrication thereof, and then introduced radially outwardly due to acentrifugal force into one-way clutchs 54 and 34, respectively. Sun gearshaft 27 has a radial hole 145 aligned with radial hole 149. Inner race90 of one-way clutch 36 has a radial hole 146. The lubricating oilintroduced through axial hole 147 and radial hole 149 in intermediateshaft 40 is admitted into one-way clutch 34 for lubrication thereof, andthen introduced radially outwardly through radial hole 146 due tocentrifugal force into one-way clutch 36 for lubrication thereof.

Referring now to the transmission gear unit 71 of the automatic speedchange-gear assembly 70, there is provided a transmission shaft orcountershaft 55 extending substantially in parallel to the intermediateshaft 40. Mounted at one end of the transmission shaft 44 is a drivengear 56 meshing with the output or driving gear 53 of auxiliary speedchange-gear assembly 11. At the other end of the transmission shaft 55there is mounted a drive gear 57. The transmission shaft 55 is rotatablysupported and carried at opposite ends thereof by bearing means, such asbearings 110 and 111, as shown in FIGS. 2a and 2b. Preferably bearings110 and 111 are roller bearings. An oil pressure governor unit 116 fordetecting speed of the motor vehicle can be mounted on transmissionshaft 55 between the drive gear 57 and driven gear 56.

Referring to FIG. 2b, a hole is provided in the left-hand end of thetransmission shaft 55 in close proximity to the auxiliary casing 74.This hole is closed by a cap 142. A snap ring 143 and an O-ring 144 arefitted in the axially outer and inner circumferential portions of cap142, respectively.

By placing the output gear 53 meshing with the driven gear 56 oftransmission gear unit 71 in the portion of the overdrive gear unit 13nearer to the engine rather than to the planetary gear unit 41, theaxially outer end portion 74b, or cap 142, of transmission gear unit 71can be indented axially inwardly toward the engine side of thetransmission. From a different perspective, the clutch unit 48 and brakeunit 49 for the overdrive unit 13 are housed in the projecting portion74a of the auxiliary casing 74 for the auxiliary speed change-gearassembly 11.

As herein embodied, the driven gear 56 of the transmission unit 71 isdiametrically larger than the drive gear 57 and has a parking gear 114formed integrally therewith. Preferably, the driven gear 56 is formedwith gear teeth 114 of the parking mechanism. When the operator of themotor vehicle shifts a shift lever to the P (parking) range, a pawl 113is brought into engagement with parking gear 114 by way of atransmission link member 112, thereby arresting the driven gear 56 in alocked position. Since the parking gear 114 is formed integrally withdriven gear 56, an increased strength in the parking gear results and noextra space for the parking gear is required.

Included as part of the transmission is a final reduction-gear assembly60. In order to position the final reduction-gear assembly 60substantially centrally in the vehicle in the lateral direction thereof,the drive gear 57 of the transmission gear unit 71 is positioned nearerto the torque converter 3 than the driven gear 56 and in mesh with agear 61 of the final reduction-gear 60. Accordingly, a drive force fromthe output gear 53 is transmitted through the transmission gear unit 71to the final reduction-gear assembly 60.

As is conventional, the final reduction-gear assembly 60 furthercomprises side gears 64, 65 meshing with pinions 66 and 67. Wheel axles62 and 63, as here embodied, extend from the side gear 64 parallel tothe axis of the auxiliary speed change-gear assembly 11. Axles 62 and 63are connected to the wheels, such as the left and right front wheels ofa motor vehicle (not shown). Shafts which rotatably support pinions 66and 67 rotate along with the gear 61. When gear 61 is driven by gear 57,the wheel axles 62 and 63 are rotated accordingly.

It may be seen that in addition to providing a compact transmission, thetransmission of this invention is also free from interference with thesuspension system of the motor vehicle. In FIG. 4, there is depictedschematically the positional relationship of the suspension system ofthe motor vehicle with the transmission system 70.

As herein embodied, a strut bar 150 of a strut-type suspension systemfor the motor vehicle is slidably provided sideways of the end portion74b and below projecting portion 74a of the auxiliary casing 74. Strutbar 150 additionally serves as a stabilizer. Wheels 117 for the motorvehicle are connected by way of a steering knuckle 119 to axle 63 and atie rod 118 in a manner to rotate freely and to be freely steered. Alower arm 120 and the strut bar 150 are connected to the steeringknuckle 119 for fixing the wheels 117 to the vehicle chassis.

As may be seen from the foregoing description of one embodiment of atransmission in accordance with this invention, there is achieved acompact transmission which has a reduced length and which is free frominterference with the suspension system of the motor vehicle.

It will be apparent to those skilled in the art that variousmodifications and variations could be made in the transmission of theinvention without departing from the scope or spirit of the invention.

What is claimed is:
 1. In a motor vehicle transmission for transmittingpower between the engine and wheel axles of said vehicle, thetransmission including:(1) a fluid-type torque converter; (2) anauxiliary speed change-gear assembly including an underdrive and anoverdrive each comprising at least one planetary gear unit, theunderdrive planetary gear unit being coaxial with and driven by thetorque converter, said underdrive being disposed between said overdriveand said torque converter, and said overdrive planetary gear unit beingcoaxial with said torque converter and said underdrive unit and havingan input element and an output element; (3) an intermediate shaftcoaxial with said torque converter and said planetary units, saidintermediate shaft extending through said speed change gear assembly anddrivingly interconnecting said underdrive planetary unit with the inputelement of said overdrive planetary unit; (4) an output gear disposedbetween said underdrive and overdrive and being coaxial with saidintermediate shaft, said output gear being drivingly fixed to the outputelement of said overdrive planetary unit; (5) a transmission gear unitincluding a counter shaft having a drive gear secured to one end thereofdrivingly meshed with said output gear, and a driven gear secured to theother end thereof; (6) a final reduction gear assembly drivinglyconnected to said driven gear and to said wheel axles for transmittingpower from said transmission gear unit to said wheel axles, said wheelaxles being substantially parallel to said intermediate shaft; and (7) acasing for enclosing said speed change-gear assembly;the improvementcomprising: (a) a radially extending flange integral with saidintermediate shaft forming a part of the input element of said overdriveplanetary unit; (b) a first thrust bearing disposed axially between saidoverdrive and said underdrive and disposed radially between saidintermediate shaft and said casing for rotatably supporting andreceiving reaction force from said intermediate shaft; (c) second andthird thrust bearings axially adjacent each other and axially disposedbetween said flange and said first thrust bearing and radially disposedbetween said intermediate shaft and said output gear for rotatablysupporting said output gear and for receiving thrust from saidintermediate shaft, said flange and said output gear, the inner race ofsaid second thrust bearing axially abutting said flange and the innerrace of said third thrust bearing axially abutting the inner race ofsaid first thrust bearing; and (d) an axially adjustable nut threadablyengaged in an opening in said casing, said nut being coaxial with saidintermediate shaft and said opening circumscribing the end of saidintermediate shaft remote from said torque converter, axial adjustmentof said nut permitting application of a predetermined axial force topreload said thrust bearings and axially position said intermediateshaft.
 2. The transmission of claim 1 wherein said second and thirdthrust bearings are counterbalancing thrust bearings.
 3. Thetransmission of claim 1 further comprising a fourth thrust bearingradially disposed between the end of said intermediate shaft remote fromsaid torque converter and said casing for rotatably supporting andreceiving reaction force from said intermediate shaft.
 4. Thetransmission of claim 3 wherein said nut axially abuts the outer race ofsaid fourth thrust bearing.